Electrochemical performance of Li3V2(PO4)3/C cathode material using a novel carbon source

Polyethylene glycol (PEG, mean molecular weight of 10,000) has been used to prepare a Li3V2(PO4)(3)/C cathode material by a simple solid-state reaction. The Raman spectra shows that the coating carbon has a good structure with a low I-D/I-G ratio. The images of SEM and TEM show that the carbon is dispersed between the Li3V2(PO4)(3) particles, which improves the electrical contact between the corresponding particles. The electronic conductivity of Li3V2(PO4)(3)/C composite is 7.0 x 10(-1) S/cm. increased by seven orders of magnitude compared with the pristine Li3V2(PO4)(3) (2.3 x 10(-8) S/cm). At a low discharge rate of 0.28C, the sample presents a high discharge capacity of 131.2 mAh/g, almost achieving the theoretical capacity (1132 mAh/g) for the reversible cycling of two lithium. After 500 cycles, the discharge capacity is 123.9 mAh/g with only 5.6% fading of the initial specific capacity. The Li3V2(PO4)(3)/C material also exhibits an excellent rate capability with high discharge capacities of 115.2 rnAh/g at 1C and 106.4 mAh/g at 5C. (c) 2009 Elsevier Ltd. All rights reserved.